In a medium saucepan, pour in 2 cups of whole milk and place over medium-low heat. Stir occasionally as the milk warms, aiming to reach a gentle simmer where small bubbles form around the edges, but do not let it boil.

Once the milk is warm, sift in 3 tablespoons of unsweetened cocoa powder and add 1 to 3 tablespoons of sugar. Using a whisk, thoroughly combine the ingredients until the cocoa and sugar dissolve completely.

Chop 4 ounces of bittersweet chocolate into small pieces and add it to the saucepan. Stir constantly with your whisk as the chocolate melts into the warm milk.

In a small bowl, mix 1 tablespoon of cornstarch with 2 tablespoons of cold water to create a smooth slurry. Set the slurry aside while you continue preparing the chocolate mixture.

While whisking continuously, slowly pour the cornstarch slurry into the hot chocolate. Keep the mixture over medium-low heat and continue stirring for about 2 to 3 minutes.

Remove the saucepan from heat and stir in 1 teaspoon of pure vanilla extract along with a pinch of salt. Give it one last whisk.

Pour your Thick Italian Hot Chocolate into mugs and top with whipped cream or other garnishes as desired.